Compressed air stapling machine for metallic staples with control of the anvil for bending the staple ends

ABSTRACT

A compressed air stapling machine for metal staples provided with an anvil for bending the fixed staples ends and means for controlling said anvil.

United States Patent Umberto Monacelli Via del Parco, Biassono (Milan), Italy 21 Appl.No. 841,216

[72] Inventor [22] Filed July 14, 1969 [45] Patented May 25, 1971 [32] Priority July 19, 1968 [33] Italy [54] COMPRESSED AIR STAPLING MACHINE FOR METALLIC STAPLES WITH CONTROL OF THE ANVIL FOR BENDING THE STAPLE ENDS 5 Claims, 9 Drawing Figs.

[52] U.S.Cl 227/124, 227/130 [51] Int. Cl B25c 5/02 [50] Field of Search 227/124, 130, 153, 155

[56] References Cited UNITED STATES PATENTS 2,687,522 8/1954 Juilfs 227/124 2,943,327 7/1960 Juilfs 227/130 3,232,511 2/1966 Crooks 227/130 3,397,828 8/1968 Volkmann 227/130 Primary Examiner-Granville Y. Custer, Jr. Attorney-Shlesinger, Fitzsimmons and Shlesinger ABSTRACT: A compressed air stapling machine for metal staples provided with an anvil for bending the fixed staples ends and means for controlling said anvil.

COMPRESSED AIR STAPLING MACHINE FOR METALLIC STAPLES WITH CONTROL OF THE ANVIL FOR BENDING THE STAPLE ENDS This invention relates to a compressed air stapling machine for metallic staples provided with an anvil for bending the staple ends.

Stapling machines of this type are known which, in addition to the principal cylinder in which the hammer-carrying piston slides for the percussion and driving of the individual metallic staples, are also provided with an auxiliary cylinder also driven by compressed air in which a piston slides which operates a lever mechanism controlling the anvil, such that the anvil moves towards the plane from which the staples are expelled, thereby clamping the material to be stapled between said plate and said anvil.

The principal disadvantages which these types of stapling machine give rise to are due mainly to the fact that the transmission of motion from the auxiliary piston to the anvil is carried out by way of a complex lever mechanism which in addition to requiring numerous linking members and various articulations, causes the approach and withdrawal of the anvil to be performed with an angular pincer movement, because of which the plane of the anvil cannot be perfectly perpendicular to the axis of the hammer and hence to the staple legs for all thicknesses of material to be stapled.

A further disadvantage is that the percussion hammer and anvil are driven by their respective pistons simultaneously or nearly simultaneously, because of which the material to be stapled is not sufiiciently clamped at the moment the staple is expelled and driven into the material and consequently the penetration of the staple is defective and often the legs of the staple are distorted inside the material and do not even arrive at the anvil for bending in a regular manner.

Finally the return of the auxiliary piston and hence the opening ofthe hammer is always dependent upon the action of a return spring.

The stapling machine which forms the object of this invention eliminates the disadvantages mentioned above. It is characterized by the fact that the auxiliary cylinder which controls the anvil is mounted coaxially or parallel and opposed to the principal cylinder that controls the expulsion of the staple, and that the anvil is rigid with the rod of the auxiliary .piston by way of a support saddle forming therewith a single piece, because of which the anvil is subjected to a rectilinear movement coaxial to the channel in the plate which guides the staples during their expulsion.

The said stirrup is slidable inside rectilinear guides parallel to said channel, and hence the anvil moves always in a straight line, thus maintaining its operating surface normal to the channel of the staple guide plate, whatever the thickness of the material to be stapled.

Another important characteristic is the fact that the closure of the anvil and the expulsion of the staple take place in two distinct successive and subordinate phases, because the lowering of the control trigger only causes or initiates action of the auxiliary cylinder and hence the clamping of the material to the staple between the anvil and the plate, while the action of the principal cylinder and consequently the expulsion of the staples is caused automatically and successively only if an when the compressed air inside the auxiliary cylinder attains the operating pressure existing in the reservoir and the other chambers in communication with it.

In this way it is always certain that the material to be stapled has been clamped right through with the desired pressure between the anvil and staple guide plate, before the metallic staple is expelled and driven.

Finally in the auxiliary cylinder a discharge port is provided at a suitable level in order to prohibit the compressed air therein from attaining the predetermined operating value if the material to be stapled is missing or if the anvil is about to finish its travel and hits against the plate through lack of material.

This constitutes a further safety measure and a control which prohibits the useless expulsion and driving of staples.

The characteristics of the stapling machine, the object of this invention, will be clearer by referring to one embodiment illustrated by way of example in the accompanying drawings in which:

FIG. 1 is a perspective view of the stapling machine;

FIG. 2 and 3 are axial sectional views of the body with the pistons in two distinct positions, at the limit in the rest position and at the limit in the working position, respectively;

FIG. 4 is a partial sectional view through the line IV-IV of FIG. 5;

FIG. 5 is a sectional view through the line V-V of FIG. 4; FIG. 6 is a sectional view through the line VIVI of FIG. 9; FIG. 7 is a sectional view through the lineVII-VII of FIG. 9; FIG. 8 is a sectional view through the line VIII-VIII of FIG.

FIG. 9 is a sectional view through the line IX-IX of FIG. 7.

The stapling machine illustrated comprises a pneumatic piston with a principal hollow body 1 which is prolonged into the hollow handle 2, which is provided with a connection 3 for connecting the body to a compressed air line, and which is fastened to magazine 4 for feeding the metallic staples. A principal cylinder 5 is mounted in the body 1 in which the piston 6 slides that is rigid with the percussion hammer 7 which, as is known, violently expels the metallic staple prearranged in the guide plate 8, when piston 6 passes from the upper rest position shown in FIG. 2 to the lower limiting position shown in FIG. 3.

On the head of body 1 is mounted an auxiliary cylinder 9 coaxially opposed to the principal cylinder 5, the piece 10 being interposed in an airtight manner between the two cylinders. The annular piston 11 is slidably mounted in the cylinder 9 and its tubular rod 12 is made rigid, by means of the yoke 13 and the bolt 14, with a double rod stirrup l5 bent at its lower end as at, 16, at the end of which is fixed the anvil 17 for riveting and bending the legs of the metallic staple after it has travelled through the material to be stapled. With the arrangement described above the anvil l7 constitutes in effect a single piece with the piston 11, and this moves with rectilinear motion along the common axis of the two cylinders 5, 9 being maintained always parallel to itself whatever the thickness of the material clamped between the plate 8 and anvil 17, as the rods slide in the rectilinear guides 18 which extend parallel to the said axis and which are secured to the sides of the body 1.

The cylindrical cavity of the tubular rod 12 is divided into two chambers 19, 20 by a piston 21 secured at the end of a coaxial tubular rod 22 rigid with the piece 10. Said tubular rod has an open hole 23 just under the piston 21.

It should be further noted that the auxiliary cylinder 9 is connected to atmosphere by way of the two holes 24 and 25.

In the piece 10 there is a chamber 26 which connects to atmosphere, by way of the port 26; the upper chamber of the distributor in which the differential valve 27 moves which controls the compressed air in the principal cylinder 5. In said chamber 26 is mounted a differential valve 28 which has its larger surface facing towards the chamber of the auxiliary cylinder 9 and which is subjected to the action of a small spring 29 which tends to keep it raised thus closing the connection between chamber 30 and port 26. The differential valve 28 causes operation of the principal piston only if the compressed air is discharged from the chamber 30, i.e. when said valve 28 passes from the rest or closed position shown in FIG. 2 to that shown in FIG. 3 and access is opened for the compressed air from the reservoir 31 to shift valve 27 slightly upwardly to the position illustrated in FIG. 3, thereby opening the upper end of the cylinder 5.

Reference numeral 32 indicates the operating trigger for moving the upper control rod 33 which is provided with a coaxial hole 34 which at one end opens into the chamber 35 and at the other end is sealed but is connected to the radial hole 36. The chamber 35 connects to the cylinder 9 by way of the holes 37, 38 (FIGS. 2 and 3).

In addition the ducts 39, 40 (FIG. 6) connect the reservoir 31 to the inside. of the tubular rod 22 by way of a hole 41 and finally (FIG. 7) a duct 42 connects the compressed air reservoir 31 to the chamber 30 situated above the differential valve 27 by way of small hole 43 and the duct 44.

Instead of the connection between the reservoir 31 and the chamber 30 being by way of the duct 42 and the hole 43, it can be more easily made by extending the axial duct of the tubular rod 22 until it is placed into communication with the chamber 30 by way of a small hole, not illustrated. This is possible because the duct of the tubular rod 22 is in permanent communication with the reservoir 31 by means of the ducts 39, 40 and 41.

The stapling machine described above operates in the following manner.

The piston 11 which controls the anvil I7 is maintained in the rest or idle position (FIG. 2) by the effect of the compressed air existing the chamber 20. At this time the lower end of the bore in cylinder 9 is exhausted through ports 38 and 37, chamber 35, and radial ports 35 to an exhaust camber which surrounds chamber 35, and which is connected to atmosphere by a port 52 in body I. Also valve 28 is closed, thereby sealing chamber 30; and valve 50, which reciprocates in an axial bore in the differential valve 27, is in its lower or open position (HO. 2), so that the upper end of cylinder is exhausted through the lower end of chamber 50' in valve 27, radial port 51 in valve 27, and ports 45, 46 and 52 to the atmosphere. By rasing the trigger 32, the control rod 33 is moved upwards and its movement closes the radial parts 35; thus blocking the discharge holes 45 and 46, whereby the compressed air travels through the hole 36 and the ducts 34, 37 and 38 in order to feed lower end of the auxiliary cylinder 9 so imposing an upward thrust on the piston 11, which being rigid with the rod 12 and the stirrup l5, l6, entrains the anvil l7 upwards so clamping the material to be stapled between the anvil itself and the plate 8. At this time it will be understood that, due to the presence of the last-mentioned material between the anvil and the plate 8, the piston 11 will be prevented from moving to its extreme uppermost positionas shown in FIG. 3..Instead, when such material is properly clamped between the anvil l7 and plate 8, the piston 11 will have stopped its upward movement at a point slightly below the port (FIG. 2) in cylinder 9, so that once the upward motion of the piston 11 ceases, the pressure in the cylinder 9 beneath the piston 11 will begin to increase to a value equal to that of the compressed air supply in reservoir 31. As soon as the air in cylinder 9 beneath the piston 11 attains the same pressure, the valve 28 opens by differential action to connect the chamber and the discharge hole 26', thus causing the upward movement of the differential valve 27 and active stroke of the principal piston 6 in the cylinder 5, and with it the driving of the metallic staple and the bending of the staple leg on the anvil (stapling phase). It is to be noted that during expansion of the compressed air in the cylinder 9 as the piston 11 rises, the valve 28 remains closed because of the force of the spring 29 and the pressure present in the chamber 30, this force being overcome only when the pressure in said cylinder attains the operating pressure level existing in the reservoir.

When the stapling phase has been thus completed, it is sufficient to release the trigger 32 in order for the rod 33 to return to its initial position (FIG. 2) under the action of the compressed air, thus initiating the return phase of all members which have moved during the stapling phase. By returning the rod 33 into the rest position, the hole 36 is closed and the discharge is opened for the air present in the cylinder 9 by way of ducts 38, 37, chamber 35, ports 35 and port 52. In this way the compressed air penetrates into the tubular rod 12 by way of the ducts 39, 40, 41, the tubular shank 22 and the hole 23, thus causing the return of the piston 11 to its initial position also entraining with it the anvil 17 into the initial opening position.

Simultaneously, as the thrust downwards on the valve 28 is removed with exhaustion of the lower end of cylinder 9, this valve is moved upwardly to its closed position by the action of the compressed air, which continues to feed the chamber 30 by way of the duct 42 and the hole 43, and by the action of the spring 29, and attains its initial position so closing communication between 30 and 26'.

The air pressure in the chamber 30 can thus increase and push the differential valve 27 downwards which closes the port of the cylinder 5. At this time the valve 50, which is operated in a known manner similar to that disclosed in my US. patent application Ser. No. 461,277, filed June 4, 1965 (now abandoned), and which prior to the downward movement of the piston 16 was moved to its upper or closed position, is once again shifted downwardly to open the lower end of chamber 50, so that the air in the cylinder 5 above the piston 6 exhausts to atmosphere through the duct 51 and the ports 45, 46 and 52. This principal piston 6 to carry out its return stroke by the known action of the thrust of the compressed air accumulated during the descending phase in the interspace 47.

The purpose of the hole 25 in the part of the cylinder 9 is to impede the stapling phase from taking place if the material to be stapled has not been placed for some reason between the anvil l7 and the plate 8.

In this case as soon as the piston 11 during its ascending stroke arrives in the position of uncovering the hole 25, the air is discharged from the cylinder 9 and operation of the valve 28 is impeded.

lclaim:

l. A compressed air stapling machine for metallic staples, comprising:

a hollow body;

means on said body for holding a supply of metal staples;

a staple guide member on said bodycommunicating with said supply means and having an opening in one end thereof through which staples are adapted to be discharged;

a principal piston reciprocable in a first cylinder in said body and having fixed thereto a percussion hammer for discharging metallic staples from said opening, and lodging them in the material to be stapled;

an auxiliary piston mounted in a second cylinder in said body to reciprocate coaxially of said principal piston;

an anvil operatively connected to said auxiliary piston for reciprocation thereby toward and away from said one end of said guide member releasably to clamp across said opening the material that is to be stapled;

a trigger mounted on said body and movable from an inoperative to an operative position thereby to connect said second cylinder to a supply of compressed air to effect movement of said auxiliary piston in one direction and simultaneous movement of said anvil toward said opening into its clamping position; and

means responsive to the air pressure in said second cylinder and operative upon movement of said auxiliary piston in said one direction, and independently of the extent of the last-named movement, and only after the air pressure in said second cylinder has attained the operating pressure of said compressed air supply, to connect said first cylinder to said compressed air supply thereby to move said principal piston in a direction to effect discharge of a staple from said opening by said hammer and stapling of the material.

2. A stapling machine as claimed in claim 1, wherein said pressure responsive means comprises:

a differential valve mounted in a chamber in said body for movement between a closed position in which it seals off said first cylinder from said compressed air supply, and an open position in which said first cylinder is connected to said compressed air supply;

means connecting opposite ends of said chamber to said air supply; and

a second, normally closed valve mounted in said body between one end of said chamber and said second cylinder normally to seal said one end of said chamber, whereby the compressed air therein operates to maintain said differential valve in its closed position;

said second valve being movable by the air pressure in said second cylinder to an open position to vent said one end of said chamber, when the air in said second cylinder reaches said operating pressure, thereby to effect move ment of said differential valve to its open position.

3. A stapling machine as claimed in claim 2, wherein:

said auxiliary piston has projecting coaxially therefrom a first tubular rod;

a stationary piston divides the bore in said rod into two sealed chambers;

said stationary piston is supported coaxially in the lastnamed bore by a second tubular rod which is fixed to one end of said second cylinder; and

said second tubular rod has its axial bore communicating adjacent one end thereof with said compressed air supply and adjacent its opposite end with one of the chambers in said first rod.

4. A stapling machine as claimed in claim 2, wherein said one end of said chamber is connected with said compressed air supply by way of a small hole for throttling the fiow of compressed air from the supply thereof to said chamber, when said second valve is open.

5. A stapling machine as claimed in claim 2, wherein said second cylinder has therein a venting hole located adjacent the end thereof toward which said auxiliary piston moves to effect clamping of the material to be stapled, whereby if the material to be stapled is missing between said anvil and said guide member, said auxiliary piston moves in said one direction beyond the last-named hole and air in said second cylinder is vented to the atmosphere thus to impede the operation of said principal piston. 

1. A compressed air stapling machine for metallic staples, comprising: a hollow body; means on said body for holding a supply of metal staples; a staple guide member on said body communicating with said supply means and having an opening in one end thereof through which staples are adapted to be discharged; a principal piston reciprocable in a first cylinder in said body and having fixed thereto a percussion hammer for discharging metallic staples from said opening, and lodging them in the material to be stapled; an auxiliary piston mounted in a second cylinder in said body to reciprocate coaxially of said principal piston; an anvil operatively connected to said auxiliary piston for reciprocation thereby toward and away from said one end of said guide member releasably to clamp across said opening the material that is to be stapled; a trigger mounted on said body and movable from an inoperative to an operative position thereby to connect said second cylinder to a supply of compressed air to effect movement of said auxiliary piston in one direction and simultaneous movement of said anvil toward said opening into its clamping position; and means responsive to the air pressure in said second cylinder and operative upon movement of said auxiliary piston in said one direction, and independently of the extent of the last-named movement, and only after the air pressure in said second cylinder has attained the operating pressure of said compressed air supply, to connect said first cylinder to said compressed air supply thereby to move said principal piston in a direction to effect discharge of a staple from said opening by said hammer and stapling of the material.
 2. A stapling machine as claimed in claim 1, wherein said pressure responsive means comprises: a differential valve mounted in a chamber in said body for movement between a closed position in which it seals off said first cylinder from said compressed air supply, and an open position in which said first cylinder is connected to said compressed air supply; means connecting opposite ends of said chamber to said air supply; and a second, normally closed valve mounted in said body between one end of said chamber and said second cylinder normally to seal said one end of said chamber, whereby the compressed air therein operates to maintain said differential valve in its closed position; said second valve being movable by the air pressure in said second cylinder to an open position to vent said one end of said chamber, when the air in said second cylinder reaches said operating pressure, thereby to effect movement of said differential valve to its open position.
 3. A stapling machine as claimed in claim 2, wherein: said auxiliary piston has projecting coaxially therefrom a first tubular rod; a stationary piston divides the bore in said rod into two sealed chambers; said stationary piston is supported coaxially in the last-named bore by a second tubular rod which is fixed to one end of said second cylinder; and said second tubular rod has its axial bore communicating adjacent one end thereof with said compressed air supply and adjacent its opposite end with one of the chambers in said first rod.
 4. A stapling machine as claimed in claim 2, wherein said one end of said chamber is connected with said compressed air supply by way of a small hole for throttling the flow of compressed air from the supply thereof to said chamber, when said second valve is open.
 5. A stapling machine as claimed in claim 2, wherein said second cylinder has therein a venting hole located adjacent the end thereof toward which said auxiliary piston moves to effect clamping of the material to be stapled, whereby if the material to be stapled is missing between said anvil and said guide member, said auxiliary piston moves in said one direction beyond the last-named hole and air in said second cylinder is vented to the atmosphere thus to impede the operation of said principal piston. 